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Earth is the only home we've ever known, and it's treated us well so far. But whether it's climate change, an apocalyptic asteroid, or some horrifying disaster we don't even know about yet, the Earth won't live forever.

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Virtually explore Mars in a fully immersive 360-degree experience.

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Video Gallery: Perseverance Rover - NASA

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Video gallery for the Perseverance rover mission that includes animations and mission trailer for all aspects of the mission.

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Mars' atmosphere is over 100 times thinner than Earth's and is primarily composed of carbon dioxide, nitrogen and argon gases.

Oxidized dust particles kicked up from the Martian surface fill the atmosphere turning Mars' skies a rusty tan color, according to NASA.

Water exists on Mars but the atmosphere is too thin for it to last long on the surface in a liquid state. Instead, water on Mars is found below the surface of the polar regions as water-ice and also as seasonal briny water flows down hillsides and crater walls.

Despite Mars' thin atmosphere, the Red Planet still exhibits a dynamic climate and extreme weather events including impressive dust storms and even snow! But Mars hasn't always been this way. NASA's MAVEN mission scientists reported that Mars once had a thick atmosphere that could have supported surface liquid water on the surface for extended periods of time.

Mars atmosphere composition

According to ESA, Mars' atmosphere is composed of 95.32% carbon dioxide, 2.7% nitrogen, 1.6% argon and 0.13% oxygen. The atmospheric pressure at the surface is 6.35 mbar which is over 100 times less Earth's. Humans therefore cannot breathe Martian air.

For crewed Mars exploration efforts, we need to find a way to generate oxygen from the thin, carbon dioxide atmosphere and an experiment carried out on NASA's Perseverance rover has demonstrated it is possible. On Apr. 20, 2021, the rover used its MOXIE (short for "Mars Oxygen In-Situ Resource Utilization Experiment") to successfully convert carbon dioxide to oxygen on Mars. "MOXIE has more work to do, but the results from this technology demonstration are full of promise as we move toward our goal of one day seeing humans on Mars." Jim Reuter, associate administrator of NASA's Space Technology Mission Directorate, said in a statement.

Martian climate and weather

(Image credit: NASA/JPL-Caltech/MSSS)

Early in its history Mars had a thick enough atmosphere for water to run on its surface. According to NASA, some surface features suggest that Mars experienced huge floods about 3.5 billion years ago.

Orbital pictures show vast river plains and possible ocean boundaries, while several Mars rovers have found evidence of water-soaked rocks on the surface (such as hematite or clay). However, for reasons that are still poorly understood, the Martian atmosphere thinned.

Mars is much colder than Earth due to the thin atmosphere and the fact it is farther from the sun. The average temperature on Mars is about minus 80 degrees Fahrenheit (minus 60 degrees Celsius), although it can vary from minus 195 F (minus 125 C) near the poles during the winter to as much as a comfortable 70 F (20 C) at midday near the equator.

Like Earth, Mars has four seasons but due to the Red Planet's eccentric orbit, the length of each season varies more than on Earth, according to NASA science.

(Image credit: NASA )

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Mars' ice caps - made of water ice and carbon dioxide, shrink and grow in response to the seasons. These seasonal changes to the ice caps affect Mars' atmosphere, which responds as one large interconnected system, according to a statement from ESA. "The lower and middle levels of Mars' atmosphere appear to be coupled to the upper levels: there's a clear link between them throughout the martian year," says Beatriz Sánchez-Cano, a planetary scientist at the University of Leicester, UK.

"Each winter, up to a third of the mass in Mars' atmosphere condenses to form an icy layer at each of the planet's poles. Every spring, some of the mass within these caps sublimates to rejoin the atmosphere, and the caps visibly shrink as a result," ESA stated.

Giant dust devils routinely kick up the oxidized iron dust that covers Mars' surface. Dust is also a permanent part of the atmosphere, with higher amounts of it in the northern fall and winter, and lower amounts in the northern spring and summer. The dust storms of Mars are the largest in the solar system, capable of blanketing the entire planet and lasting for months. These usually take place in the spring or summer.

(Image credit: NASA/JPL-Caltech/MSSS)

These dust storms can play havoc with Mars exploration missions and can even ground flights (yes Earth isn't the only planet where flights can be delayed due to poor weather!). NASA's Ingenuity Mars helicopter was due to make its 19th flight on the Red Planet on Jan. 5, 2022, when a dust storm near Jazero Crater had other plans.

"Most notable was a sharp drop in air density - about a 7% deviation below what was observed pre-dust storm," Jonathan Bapst and Michael Mischna, of Ingenuity's weather/environment team, said in a statement. "This observed decrease would have put density below the lower threshold of safe flight and would have imparted undue risk to the spacecraft. We also observed the effect of dust in the amount of sunlight absorbed by Ingenuity's solar array, which fell well below normal 'clear sky' levels, a drop of about 18%." Over a month passed until Ingenuity was clear to fly again, finally acing its 19th flight on Feb. 8, 2022.

One theory as to why dust storms can grow so big on Mars starts with airborne dust particles absorbing sunlight, warming the Martian atmosphere in their vicinity. Warm pockets of air flow toward colder regions, generating winds. Strong winds lift more dust off the ground, which in turn heats the atmosphere, raising more wind and kicking up more dust. A 2015 study further suggested that the momentum of Mars - which is affected by other planets - generates planet-circling dust storms when that momentum is at its greatest during the early part of the dust storm season.

At times, it even snows on Mars. The Martian snowflakes, made of carbon dioxide rather than water, are thought to be very small particles that create a fog effect rather than appearing as falling snow. The north and south polar regions of Mars are capped by ice, much of it made from carbon dioxide, not water.

How did Mars lose its atmosphere?

(Image credit: NASA's Goddard Space Flight Center )

At some point in Mars' history, the Red Planet lost much of its atmosphere, transforming it from a warm wet world to the cold arid plains we see today, said ESA in a statement

Mars' atmosphere continues to "leak" out into space but how?

The leading theory is that Mars' light gravity, coupled with its lack of global magnetic field, left the atmosphere vulnerable to pressure from the solar wind, the constant stream of particles coming from the sun. Over millions of years, the sun's pressure stripped the lighter molecules from the atmosphere, thinning it out. This process is being investigated by NASA's MAVEN (Mars Atmosphere and Volatile Evolution) mission. Other researchers hypothesize that perhaps a giant impact by a small body would have stripped the atmosphere away.

Mars atmosphere expert Q&A

We spoke to Timothy A. Livengood, an observational planetary astronomer about Mars' atmosphere.

How and why might the composition of Mars's atmosphere change periodically (for instance, over the course of a day, seasonally, etc.)?

Why do scientists think that Mars used to have a much thicker atmosphere?

Besides thickness, how might Mars's atmosphere be different from its atmosphere when it was a more Earth-like planet?

How can scientists learn more about what the Martian atmosphere used to be like?

Additional resources

If you would like to see where NASA's Maven mission is right now check out their mission page with a real-time simulated view of the spacecraft. Interested in terraforming? Check out our article on whether we can terraform Mars to make it more hospitable. Explore the science of becoming "Interplanetary" with this engaging article from Interesting Engineering.

Bibliography

Ramstad, Robin, et al. "Global mars‐solar wind coupling and ion escape." Journal of Geophysical Research: Space Physics 122.8 (2017): 8051-8062.

Sánchez‐Cano, Beatriz, et al. "Spatial, seasonal, and solar cycle variations of the Martian Total Electron Content (TEC): Is the TEC a good tracer for atmospheric cycles?." Journal of Geophysical Research: Planets 123.7 (2018): 1746-1759.

Smith, David E., Maria T. Zuber, and Gregory A. Neumann. "Seasonal variations of snow depth on Mars." Science 294.5549 (2001): 2141-2146.

Banfield, Don, et al. "The atmosphere of Mars as observed by InSight." Nature Geoscience 13.3 (2020): 190-198.

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Mars' Atmosphere: Composition, Climate & Weather

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Mars' atmosphere is over 100 times thinner than Earth's and is primarily composed of carbon dioxide, nitrogen and argon gases.

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Why do we care about water on Mars? :: NASA Space Place

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Where there are signs of water, there might also be signs of life!

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Putting boots on Mars is the chief long-term goal of the international human spaceflight community.

Credit: NASA/JSC

The idea of living on Mars has been a staple of science fiction since the 19th century, when American astronomer Percival Lowell speculated that the channels on the Red Planet were really ancient canals built by intelligent extraterrestrials.

But if this sci-fi dream were to ever become reality, what would it be like to actually live on Mars?

In 1965, NASA's Mariner 4 spacecraft completed the first Martian flyby, and six years later, the Soviet Union's Mars 3 lander became the first spacecraft to land softly on Mars. Since then, there have been numerous successful missions to the Red Planet, including the deployment of four Mars rovers - the now-defunct Sojourner and Spirit, and the still-active Opportunity and Curiosity - and NASA's Mars Odyssey spacecraft, which produced a map of the entire planet. [ How Living on Mars Would Be Challenging (Infographic)]

NASA is now planning for a manned mission to Mars, which is slated for the 2030s.

It's unknown where astronauts will land on Mars for that mission, but for a future Martian space colony, "you'd probably want a permanent base somewhere in the low northern latitudes," Ashwin Vasavada, a deputy project scientist for NASA's Mars Science Laboratory, told Space.com.

Like Earth, Mars has seasons due to the planet's tilt upon its axis, but it also has a secondary seasonal effect because of its highly elliptical orbit. The southern hemisphere is pointed away from the sun when the planet is farthest from it, resulting in far colder winters (and far hotter summers) than those in the northern hemisphere.

If you were to live in the northern hemisphere, you'd enjoy about seven months of spring, six months of summer, a little more than five months of fall and only about four months of winter. (A year on Mars is about 1.88 Earth years, and a day lasts a little more than 24 hours.)

The average temperature on Mars is minus 80 degrees Fahrenheit (minus 60 Celsius), but temps can range from minus 195 F (minus 126 C) in winter near the poles to 68 F (20 C) during summer near the equator. The temperatures can also change dramatically within a single week.

Mars' temperature variations often result in powerful dust storms, which can sometimes shroud the entire planet after just a few days. Though these storms probably wouldn't physically harm you, the dust could clog electronics and interfere with solar-powered instruments, Vasavada said.

At just 1 percent the density of Earth's atmosphere, the Martian atmosphere is thick enough to burn up meteors smaller than marbles - meteors larger than that are relatively rare, so you'd be unlikely to get hit by them, Vasavada said. You also wouldn't have to worry much about volcanic and tectonic activity while living on Mars.

"The No. 1 thing an astronaut would be worried about is the radiation from space," Vasavada said. Unlike Earth, Mars doesn't have a global magnetic field and thick atmosphere to protect its surface from radiation.

If you were to experience some unfortunate incident, a message sent home to Earth would take an average of 15 minutes to get there. While not terribly long, "it's definitely annoying enough that it'd be hard to Skype with anybody," Vasavada said.

In terms of weather, you might see an occasional wispy cloud or cold morning frost because Martian air contains low levels of moisture from the polar ice caps. But you wouldn't find any storm clouds in the sky or raindrops hitting the ground.

With these clear skies, the Martian night is full of stars. Amateur astronomers would want to look out for Mars' moons, Deimos and Phobos, which can come out at the same time. These satellites, both of which are far smaller than Earth's moon, can also partially eclipse the sun during the day.

The daytime sky generally has an orange tint to it because of all the dust, Vasavada said. Sunrise and sunsets look similar to those on Earth during a very hazy day, except that the area around the sun is blue.

The surface of Mars offers up a few great opportunities for sightseeing. "If we were to completely colonize Mars, there are certainly places that would become national parks," Vasavada said.

For example, Olympus Mons is the tallest volcano in the solar system, reaching 16 miles (25 kilometers) above its surrounding plains. Valles Marineris, on the other hand, is a giant system of valleys about the distance from Los Angeles to New York. And you'd also probably want to visit the Viking landers and Mars' tremendous polar ice caps, which sometimes get dry ice snowfall, Vasavada said.

But with a gravity that's only 38 percent of Earth's, getting around on Mars would be challenging at first. "Running and fast movements would probably take quite a bit of relearning," Vasavada said. "But it'd be better than moving around on the moon."

Editor's note: This is Part 3 in Space.com's 12-part series " Living on Other Planets: What It Would Be Like" to see what an astronaut would see on other planets and moons of our solar system and beyond. Check back each Tuesday to see what humans might encounter on other cosmic bodies in the universe.

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The idea of living on Mars has been a staple of science fiction since the 19th century, when American astronomer Percival Lowell speculated that the channels on the Red Planet were really ancient canals built by intelligent extraterrestrials. But if this sci-fi dream were to ever become reality, what would it be like to actually live on Mars?